1. Field of the Invention
This invention relates in general to a protective overcoat for data storage disks, and more particularly to a method for producing a disk having an overcoat with two regions of different thickness.
2. Description of Related Art
The demand for increased areal density in magnetic storage pushes thin film disk scientists to reduce the spacing between the magnetic layer on the disk and the magnetic transducer in the slider. Since the protective overcoat on the disk lies between the slider and the magnetic layer its thickness must be minimized without compromising wear and corrosion resistance. Sputtered carbon based thin films, which typically include hydrogen and sometimes nitrogen, have been used extensively within the industry for overcoats. Many other materials have been used or suggested as overcoat materials as well. The overcoats are typically subjected to higher stress when the disk first begins to rotate and when it is slowing to a stop. During these start/stop periods the slider may be in contact with the overcoat. The wear resistance of the overcoat to these and other stresses improves with increased thickness. To improve magnetic characteristics for data storage, protective overcoats have been developed that have a film thickness that is greater in a reserved contact start/stop (CSS) zone. This CSS zone is typically located at the inner diameter of the disk.
While methods for producing these different zones of overcoat thickness have been disclosed, prior techniques produce an unwanted, wide sloping transition between the thicker and thinner zones.
It can be seen that there is a need for a method for producing a protective overcoat that provides a more rapid transition between the thicker overcoat region over the landing zone and the thinner overcoat region over the data recording zone.
It can also be seen that there is a need for a method for producing a protective overcoat that provides increased contact start/stop durability by facilitating an increase in the overcoat over the landing zone while facilitating a reduction in the thickness of the overcoat over the data recording zone.